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The Synthesis and Characterization of Nanostructures Based-on Biomolecules

Author: LiNa
Tutor: GaoFaMing
School: Yanshan University
Course: Applied Chemistry
Keywords: DNA cyt c insulin amyloid fibrils ZnO BaWO4 ultrathin Pt nanowires anti-tumor activity electrocatalytic activity
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Type: PhD thesis
Year: 2012
Downloads: 161
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Abstract


Morphology-controlled synthesis of inorganic nanostructures has attracted significantinterest due to the importance of the geometrical forms of materials in determining theirwidely varying properties. For this to be realized, a major advance would be to devise amethod for constraining the growth of materials into desirable geometrical forms. Amongthese techniques, biomolecules can physically guide nanoscale structures into complexpatterns or geometries due to their varied nanoscale structures. In this paper, we, for thefirst time, chose DNA, cyt c and insulin amyloid fibrils, as the templates to control thesynthesis of uniform ZnO nanoparticle chains and BaWO4nano pair-linear arrays, and thegrowth and assembly of Pt nanoclusters and ultrathin Pt nanowires. The details and resultsare summarized as follows:The controllable nucleation and growth of ZnO nanoparticle chains were realizedbased on the assistance of DNA. The size distribution of ZnO nanoparticles can becontrolled by adjusting the concentration of reagents. The bandgap energies determinedfrom UV-vis absorption spectra show a significant quantumsize efect, and we have used achemical bond theory of quantum size efects of semiconductor nanocrystals to study thevariation of the bandgap energy with the size of the ZnO nanocrystals. Photoluminescenceinvestigation reveals that DNA has the direct and efcient passivation efect on the defectsor traps on the surface of ZnO nanoparticles. Infrared spectroscopy exploits the fact thatphosphate groups presented on DNA molecules serve as useful ligands to control thegrowth of ZnO nanoparticle chains. A possible mechanism for the formation of ZnOnanoparticle chains on DNA template was discussed based on the structural property ofDNA and the obtained experimental results.We create BaWO4nano pair-linear arrays based on the structural andphysicochemical properties of DNA which can lead DNA to separate the double strandsclose to denaturation. The influences of temperature and the reagent concentrations on thegrowth of BaWO4nano pair-linear arrays were studied. Raman spectra indicate the highSRS gain coefficient during the SRS process. UV-vis absorption spectra of varying the oligonucleotide on the results of BaWO4nanocrystal synthesis were studied, andindicating oligo（dA） play a key role to serve as a competent ligand for nucleation, growth,and capping of BaWO4nanocrystals. On the basis of these results, we propose a generalmechanistic framework describing how DNA promote and control BaWO4nanopair-linear arrays growth.In this study, cyt c was successfully used as building blocks for constructingpearl-like chains of Pt nanoclusters. The samples were characterized by TEM, XRD,UV-vis, and FTIR, etc.. The influences of reagent concentrations, reduction degree, pH,and incubation time on the growth of products were studied. FTIR spectra indicateamino-group on cyt c is the functional ligand to control the growth of pearl-like chains ofPt nanoclusters. The molecular mechanisms responsible for the formation of Ptnanoclusters on the surface of cyt c were further investigated in our study. Meanwhile, theinfluences of cyt c/Pt complex on the tumor inhibition rate, tumor cell apoptosis, and thetoxicity towards liver and kidney were also studied. The results indicate cyt c/Pt complexhas obvious anti-tumor properties, whereas lower toxicity towards liver and kidney.We investigate the use of insulin amyloid fibrils （INSAFs） as scafolds to control thesynthesis of ultrathin Pt nanowires （UTPtNWs）. The influences of pH, reductants, andreagent concentrations on the growth of UTPtNWs were also studied. The morphologyand the structure of UTPtNWs were characterized by TEM, HRTEM, EDS, XRD, andSAED, etc.. Cyclic voltammetry tests reveal that UTPtNWs present favorableelectrocatalyst properties, and their electroactive surface areas are found3times higherthan that of the commercial Pt/C catalyst. The methanol oxidation reaction activity of theUTPtNWs is18%higher than that of the commercial Pt/C catalyst. The UTPtNWs alsomaintain excellent electrochemical durability under repeated cyclic voltammetry scans.Based on these experimental results and complex theory, a possible mechanism for theformation of UTPtNWs based-on INSAFs was also discussed.

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